Changing spark plugs,struggling to get like for like champion items,RG4HC,dealer cross references to NGK equivalent,threaded part and porcelain part are same length but body where the hexagon is is shorter,will this be ok or with it sitting further down in the cylinder head would the cap/coil not connect properly
Someone else will probably confirm, I think it's something to do with difficulty getting the spark plug socket onto the NGK plugs.
There also a subtle but IMO, significant, difference in the amount the electrode projects into the combustion chamber. The NGK is recessed further and therefore starts the burn in the plug recess. I use NGK throughout the jobs in my shop, but always use champion on the 749/999 motors. The fitting is also an issue that can cause grief for the home service. Any Ducati dealer should be able to supply you. If you struggle, drop me a PM. I have stock
I just fitted the NGK plugs but haven’t run it yet. Coil sticks seemed to “click” onto the plugs just fine. If the Champion plugs weren’t many times the price of the NGK (or if NGK wasn’t a proven brand) I would have gone with the Champion plugs. I tapered a 16mm deep well socket in a drill press with a file and this worked quite well with the NGKs.
I found one by Teng Tools ( my original tool roll got stolen ) . Bought online last year for about £6 Good quality and a nice easy fit down the bore hole , the only snag is that I have to tape it to the extension bar because the socket tends to stay put with the plug when replacing it .
I’ve also got Tengtools, very nice stuff! Anyway, my 16mm socket doesn’t seem to fit the spark plugs in my 749 engine so I’m curious which one you have. I’ve got the 3/8” set..
It's a 16 mm socket with 1/2" drive , and the overall length is around 65 mm There's a slim well-made rubber collar inside it . In case it helps anyone , I measured the outside diameter earlier , it's 21.55 mm ( but it's often not quoted by online sellers ) I remember doing a lot of searching to match the specs I wanted .....
A 16mm version. You can a get shorter length also. https://www.ebay.co.uk/itm/T322216-...Socket-Thin-Wall-3-8-Drive-16mm-/312330267774
